Weight trades in the design of a composite wing box: effect of various design choices

Abstract

A process to efficiently design composite wing boxes is presented. It uses analytical and semi-empirical equations for failure modes such as material strength, plate buckling, stiffener column buckling and stiffener flange or web crippling. Laminate layups for the different components are selected in accordance with basic engineering rules and guidelines and are updated as necessary to meet the local loads. The emphasis is in allowing buckling of skins at any fraction of the ultimate load and allowing local load redistribution from buckled to non-buckled panels to save weight. The design process is automated and the design can be automatically transferred over to a commercial finite-element code for detailed design and validation. The effects on weight of number of spars, ribs, and stiffeners as well as the fraction of ultimate load at which buckling is allowed are examined and insight is gained to which of these the weight is most sensitive to. In addition, the effect of minimum gage on weight was found to be a driver.

A new parameter to describe crippling strength: Experimental and theoretical investigations for post‐buckling behaviors of the composite structures

“…In other words, the equilibrium is conserved, and the body returns its stable condition at any disturbances in this stage. [1][2][3][4] However, when the entire load carrying capacity of the structure is considered, it is experienced that the structure is able to resist more load than carried in pre-buckling phase. [5][6][7][8] In order to take the advantages of more load carrying potential of the members, the load is increased and critical buckling threshold is exceeded.…”

Skin Panel Optimization of the Common Research Model Wing Using Sandwich Composites

“…Practical experience shows that their benefits come alongside a number of unique engineering challenges, which must be carefully considered in realistic designs [13]. The potential advantages and challenges have motivated a wide range of research covering topics such as characterization of failure modes [14][15][16], development of modelling strategies [17,18] and on optimization of sandwich composites [10][11][12][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Some of the relevant literature pertaining to the latter have been discussed further.…”

Computation of dimensional variations on the structural analysis of multi-cell aircraft box beams with python scripting

“…Unsymmetric beam sections require the use of unsymmetric beam bending equations (Krenk and Hogsberg, 2013). During the preliminary design phase of an aircraft, any identical change in stiffener sectional properties or uniform dimensional variations in spar or panel sections would be handled easily with computer codes (Marczi and Smrcek, 2004; Moors et al , 2019; Zhu et al , 2019). Among them, python scripting yields one of the most powerful solutions to be easily served for verification purposes due to its versatility (Petsch et al , 2018; Cmirman et al , 2019).…”